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Biomedical subjects

J B Towne

Publications and source records attributed to J B Towne.

At least 55 records · Page 3Linked to original sources
PubMed1995

Healing of venous ulcers in an ambulatory care program: the roles of chronic venous insufficiency and patient compliance.

PURPOSE: A nurse-managed/physician-supervised treatment program for venous ulceration was evaluated to determine the influence of venous hemodynamics, comorbidities, patient behavior, and ulcer characteristics on time to healing and time to recurrence. METHODS: The clinical course and long-term follow-up of 71 patients with 99 venous ulcers diagnosed between November 1981 and August 1994 were analyzed by a retrospective review of clinic records. Demographic data, severity of venous insufficiency, ulcer characteristics, and patient compliance were studied. Outcome variables were time to complete ulcer healing and time to first recurrence. RESULTS: Ninety-one percent of the ulcers healed completely at a median 3.4 months. There were 52 (57%) recurrences at a median 10.4 months. Ulcers on limbs with a venous refill time of 10 seconds or less demonstrated a significantly longer time to complete healing (p < or = 0.03); however, no effect on time to recurrence was observed. Patients who were in strict compliance with the treatment regimen (n = 32) had significantly faster healing (p < or = 0.02) and fewer recurrences (p < or = 0.004) compared with patients who were less compliant (n = 67). CONCLUSIONS: Most venous ulcers can be expected to heal when patients are enrolled in a nurse-managed/physician-supervised ambulatory ulcer clinic. Photoplethysmography-derived venous refill time of 10 seconds or less predicted delayed healing. Strict compliance with the treatment protocol significantly decreased the time to healing and prolonged the time to recurrence.

Adult↗
PubMed1994

Acute aortic dissection into a preexisting abdominal aortic aneurysm.

Acute aortic dissection and abdominal aortic aneurysm presenting as coexistent conditions is rare. We report a patient with a history of hypertension and acute severe back pain who had an acute aortic dissection extending into a preexisting 8 cm abdominal aortic aneurysm that was diagnosed by CT scan. There was no evidence of aortic rupture or leakage. The patient was treated with antihypertensive medication for 2 months to allow maturation of the acute dissection prior to elective repair of the abdominal aortic aneurysm. The repair was constructed to allow continued perfusion of both the true and false lumina by fenestration of the aortic septum at the proximal anastomosis. There were no postoperative complications. This case illustrates an unusual combination of aortic diseases. A management plan is described that safely treats both pathologic conditions.

Acute Disease↗
PubMed1994

In situ replacement of arterial prosthesis infected by bacterial biofilms: long-term follow-up.

PURPOSE: Bacterial biofilm infections of vascular prostheses are characterized by an absence of systemic sepsis, a fluid-filled cavity surrounding the graft, a draining sinus tract, and microorganisms that must be removed from the fabric prosthesis for bacterial culture. METHODS: Since 1987 we have treated 20 infected grafts with prosthetic excision and in situ replacement in 14 men and 6 women. The time from initial graft implantation to diagnosis of graft infection ranged from 3 months to 14 years (mean 4.5 years). The original graft (Dacron-17, polytetrafluoroethylene-3) was an aortobifemoral in 14, axillofemoral femorofemoral in 3, iliofemoral in 2, and femoropopliteal in 1 patient. Presenting symptoms were groin false aneurysm with perigraft fluid in 10, inflammatory mass in 6, and sinus tract in 4. At surgery all unincorporated graft material and the perigraft capsule were excised from a point where the proximal graft was incorporated, including debridement of vessels at the distal anastomosis. Of the 14 aortobifemoral grafts, only the femoral limbs were excised at the initial presentation of biofilm infection. The conduit was replaced with an in situ polytetrafluoroethylene interposition graft, which was covered with a gracilis or sartorius muscle flap when possible. RESULTS: All surgical sites healed, all grafts remained patent, and there was no limb loss. After ultrasonic oscillation of the explanted graft, bacterial cultures recovered coagulase-negative Staphylococcus species in 14, coagulase-positive Staphylococcus species in one, both species in three, with no growth from two specimens. During follow-up, two patients have had clinical involvement in the proximal intraabdominal portion of the graft that had not been previously resected. In all grafts, the in situ replacement graft remained well incorporated. CONCLUSION: In situ graft replacement is effective treatment for biofilm infections of vascular prostheses. Because of the indolent nature of these infections, subsequent infection of previously uninvolved graft segments may be expected.

Bacterial Adhesion↗
PubMed1994

4. Current status of operative treatment for asymptomatic carotid stenosis.

OBJECTIVE: To determine the natural history of asymptomatic carotid stenosis and the effect of prophylactic carotid surgery on neurologic morbidity and mortality. DESIGN: A prospective, randomized, cooperative study, with a mean follow-up of 47.9 months. SETTING: Ten Veterans Administration hospitals across the United States. PATIENTS: The study comprised 436 patients who were divided into two groups: group 1, patients with symptomatic unilateral carotid disease, who were treated with carotid endarterectomy, and had contralateral asymptomatic stenosis; group 2, patients with significant asymptomatic carotid disease. Carotid stenosis was confirmed by arteriography, which demonstrated at least 50% stenosis, measured by comparing the least transverse diameter of the stenosis on lateral arteriography. INTERVENTIONS: Ocular plethysmography, duplex scanning and arteriography; carotid endarterectomy and acetylsalicylic acid or acetylsalicylic acid alone. RESULTS: The 436 patients were randomized between nonoperative (medical) (233) and operative (surgical) (211 procedures on 203 patients) groups. In the surgical group, the 30-day mortality was 1.9% and the permanent neurologic morbidity was 2.4%, for a combined stroke and death rate of 4.3%. The incidence of neurologic events was 8% in the surgical group compared with 20.6% in the medical group, for an absolute reduction in risk of 12.6% (p < 0.001). CONCLUSION: Carotid endarterectomy, combined with optional medical management, can reduce the incidence of ipsilateral neurologic events in high-risk men with arteriographically confirmed asymptomatic carotid stenosis.

Aspirin↗
PubMed1993

Efficacy of carotid endarterectomy for asymptomatic carotid stenosis. The Veterans Affairs Cooperative Study Group.

BACKGROUND: The efficacy of carotid endarterectomy in patients with asymptomatic carotid stenosis has not been confirmed in randomized clinical trials, despite the widespread use of operative intervention in such patients. METHODS: We conducted a multicenter clinical trial at 11 Veterans Affairs medical centers to determine the effect of carotid endarterectomy on the combined incidence of transient ischemic attack, transient monocular blindness, and stroke. We studied 444 men with asymptomatic carotid stenosis shown arteriographically to reduce the diameter of the arterial lumen by 50 percent or more. The patients were randomly assigned to optimal medical treatment including antiplatelet medication (aspirin) plus carotid endarterectomy (the surgical group; 211 patients) or optimal medical treatment alone (the medical group; 233 patients). All the patients at each center were followed independently by a vascular surgeon and a neurologist for a mean of 47.9 months. RESULTS: The combined incidence of ipsilateral neurologic events was 8.0 percent in the surgical group and 20.6 percent in the medical group (P < 0.001), giving a relative risk (for the surgical group vs. the medical group) of 0.38 (95 percent confidence interval, 0.22 to 0.67). The incidence of ipsilateral stroke alone was 4.7 percent in the surgical group and 9.4 percent in the medical group. An analysis of stroke and death combined within the first 30 postoperative days showed no significant differences. Nor were there significant differences between groups in an analysis of all strokes and deaths (surgical, 41.2 percent; medical, 44.2 percent; relative risk, 0.92; 95 percent confidence interval, 0.69 to 1.22). Overall mortality, including postoperative deaths, was primarily due to coronary atherosclerosis. CONCLUSIONS: Carotid endarterectomy reduced the overall incidence of ipsilateral neurologic events in a selected group of male patients with asymptomatic carotid stenosis. We did not find a significant influence of carotid endarterectomy on the combined incidence of stroke and death, but because of the size of our sample, a modest effect could not be excluded.

Adult↗
PubMed1993

Durability of the in situ bypass following modification of abnormal vein segment.

Modification procedures performed during in situ bypass grafting to correct an injured or inadequate saphenous vein segment result in a significant increase in the incidence of vein graft complications in the follow-up period. Modification procedures were performed in 96 in situ saphenous vein bypasses and consisted of primary closure (n = 28), vein patch angioplasty (n = 31), or resection and/or replacement (n = 37). At 4 years primary patency was 54%, secondary patency was 73%, and limb salvage was 89%. The incidence of subsequent vein graft stenosis and revision or graft failure was similar for grafts requiring vein patch angioplasty (7 of 31, 23%), primary repair (9 of 28, 32%), and resection and/or replacement (16 of 37, 43%) (p not equal to ns). Only 4 bypass revisions were performed for stenosis at the site of the original modification procedure. The type of vein graft repair did not significantly affect the primary patency at 18 months (primary closure, 65%, vein patch angioplasty, 66%, and resection and/or replacement, 58%) or the secondary patency at 30 months (primary closure, 80%, vein patch angioplasty, 90%, and resection and/or replacement, 77%). Modified autogenous conduits maintain patency and limb salvage but are prone to develop graft complications in the follow-up period.

Coronary Artery Bypass↗
PubMed1993

Determinants of successful peroneal artery bypass.

PURPOSE: The purpose of this study was to identify the determinants of long-term success with the peroneal artery bypass. METHODS: Seventy-seven consecutive peroneal artery bypasses performed between 1981 and 1990 were reviewed to evaluate the influence of venous conduit modification, surgeon experience, patency of the dorsalis pedis or posterior tibial artery at the ankle, and the quality of the peroneal collateral branches and pedal arch. The average follow-up was 34 months (range 1 to 92 months). RESULTS: The 5-year primary and secondary patency rates were 61% and 92%, respectively. Modification of the vein graft at the initial procedure was necessary in 26 (34%). This led to a reduced (p < 0.001) 5-year primary patency rate of 22% compared with 80% for unmodified conduits. Operative results improved with surgeon experience. The 5-year secondary patency rate of grafts placed before 1985 was 82% compared with 98% for subsequent grafts (p < 0.03). The initial postoperative mean ankle/brachial index for grafts revised for hemodynamic failure or thrombosis in the follow-up period was 0.84 compared with 0.95 in grafts that did not require revision (p < 0.04). The presence of a patent dorsalis pedis or posterior tibial artery at the ankle and an intact pedal arch did not significantly influence primary or secondary patency. The 5-year secondary graft patency rate for patients with a patent dorsalis pedis or posterior tibial artery at the ankle was 88%. CONCLUSIONS: The peroneal artery should be selected for outflow when it is the single tibial runoff vessel and is preferable to a bypass to an inframalleolar arterial segment. The quality of the venous conduit and the technical skill of the surgeon are the two most important factors in the success of bypasses to the peroneal artery.

Aneurysm↗
PubMed1993

Biologic characteristics of long-term autogenous vein grafts: a dynamic evolution.

PURPOSE: The venous conduit as an arterial substitute has dynamic biologic properties that affect its durability. This study evaluated the morphologic and physiologic characteristics of 72 lower extremity vein grafts functioning at 4.5 to 21.6 years (median 6.6 years). METHODS: The entire graft was imaged with use of color duplex ultrasonography and then classified as normal (class I), abnormal but not graft-threatening (class II), or abnormal and graft-threatening (class III) for the proximal, middle, and distal thirds. Thirty-one grafts (43%) were classified as normal, whereas 41 (57%) were classified as abnormal, with 58 class II and 15 class III segments. RESULTS: Three types of abnormalities were found by duplex imaging: nonstenotic wall plaques, discrete stenoses, and aneurysmal dilation. Aneurysms developed in five of seven grafts that had required thrombectomy in the distant past (mean of 40 months). There were 70 postoperative revisions in 38 limbs (53%). In 23 (60%) the conduit was revised, in 11 (29%) the revisions corrected progression of native artery atherosclerotic disease, and in 4 (11%) both types of revisions were required. Eleven grafts were revised in the first 30 days to correct technical errors. Eighteen limbs were revised between 1 and 24 months, with 12 (67%) of the revisions correcting stenotic lesions in the conduit or at one of the anastomoses. After 24 months 12 (67%) of 18 limbs were revised to correct progression of occlusive disease in the inflow or outflow vessels. At the time of this study 18 (67%) of the 27 conduits revised for intrinsic lesions were abnormal by color duplex imaging, and they harbored 12 (80%) of the 15-graft-threatening lesions. CONCLUSIONS: Autogenous vein remains the most durable arterial conduit, but vigilant surveillance is essential because the atherosclerotic environment continually produces lesions that may imperil the longevity of the graft.

Adult↗
PubMed1993

The importance of intraoperative detection of residual flow abnormalities after carotid artery endarterectomy.

PURPOSE: The efficacy of carotid endarterectomy in the prevention of strokes mandates low perioperative morbidity, as well as a low incidence of late ipsilateral stroke. This prospective study involving 430 patients (461 carotid endarterectomies) correlated the results of intraoperative assessment with end points of stroke and residual/recurrent internal carotid artery (ICA) stenosis. METHODS: Adequacy of the repair was assessed by ultrasound studies (duplex scan and pulsed Doppler spectral analysis) alone (n = 142), ultrasound studies and arteriography (n = 268), or clinical inspection (n = 51). After operation, duplex ultrasonography was used to confirm patency and categorize severity of ICA stenosis. At operation 26 carotid endarterectomy sites (5.6%), were revised based on intraoperative studies. RESULTS: Perioperative (30-day) morbidity rates were similar in patients with normal, mildly abnormal, or no ultrasound completion studies. There were six permanent (1.3%) and 12 temporary (2.6%) neurologic deficits and six deaths, including four fatal strokes and two fatal myocardial infarctions. By life-table analysis, the incidence of greater than 50% diameter-reducing ICA stenosis or occlusion was increased (p < 0.007, log-rank test) in patients with residual flow abnormality or no study. More important, patients with normal intraoperative flow studies had a significantly lower rate of late ipsilateral stroke compared with the remaining patient cohort (p = 0.04, log-rank test). During the mean 30-month follow-up interval, the incidence of late stroke was increased (p = 0.00016) in patients with ICA restenosis or occlusion (3/35) compared with patients without recurrent stenosis (3/426). CONCLUSION: Confirmation of a normal repair at operation affords the best opportunity to minimize ischemic neurologic events and anatomic restenosis after carotid endarterectomy.

Blood Flow Velocity↗
PubMed1993

Treatment of bacteria-biofilm graft infection by in situ replacement in normal and immune-deficient states.

PURPOSE: Complications of grafts infected with coagulase-negative staphylococci can be eradicated by antibiotic administration, tissue debridement, and in situ graft replacement, but successful treatment may be diminished in a setting of altered immune function. METHODS: In a canine model of an established aortic graft infection from Staphylococcus epidermidis, outcomes after in situ replacement were compared between normal dogs and animals made immune-deficient by administration of azathioprine (50 mg/day) and prednisone (10 mg/day). In situ replacement of an infected infrarenal aortic graft with either antibiotic-bonded (silver-ciprofloxacin: Ag-cipro) or conventional polytetrafluoroethylene (PTFE) grafts was performed in 17 control and 18 immune-deficient animals. RESULTS: Four weeks after implantation of a Dacron graft colonized with a biofilm of S. epidermidis, all study animals demonstrated a bacterial biofilm infection with perigraft inflammation or abscess, and in immune-suppressed dogs the incidence of perianastomotic aortitis was increased (p < 0.05). Six weeks after in situ replacement both the Ag-cipro and conventional PTFE grafts were healed without signs of infection in controls, but anatomic evidence of persistent infection and increased S. epidermidis recovery was observed in immune-suppressed animals that underwent in situ replacement of a standard (five of seven) versus antibiotic-bonded (one of 11) PTFE graft (p < 0.006). Overall in situ replacement with an antibiotic-bonded graft yielded a lower frequency of S. epidermidis recovery (two of 19 Ag-cipro graft biofilm with positive culture results versus nine of 16 conventional graft biofilm with positive culture results; (p < 0.003). CONCLUSIONS: This study supports the efficacy of in situ replacement for low-grade graft infections caused by S. epidermidis in normal hosts and demonstrates superiority of antibiotic-bonded grafts in immune-deficient hosts.

Animals↗
PubMed1993

Symptomatic recurrent carotid stenosis and aneurysmal degeneration after endarterectomy.

BACKGROUND: Aneurysmal degeneration of a carotid reconstruction was not recognized until the patient, who was known to have recurrent carotid artery stenosis, had a thromboembolic stroke. This sequelae of carotid endarterectomy is a serious complication, associated with a high morbidity and mortality rate. This review was conducted to establish the risk of transient ischemic attack and stroke for patients found to have recurrent carotid stenosis associated with aneurysmal degeneration of the carotid artery after endarterectomy. METHODS: A case is reported, and 100 literature references of aneurysmal degeneration of the carotid artery after endarterectomy were reviewed. RESULTS: False aneurysm from anastomotic disruption was the most common presentation identified in the cases reviewed. Nineteen of the patients had a significant neurologic event; however, three (50%) of six patients with aneurysm and recurrent carotid artery stenosis had a transient ischemic attack or stroke. CONCLUSIONS: The incidence of neurologic symptoms is markedly increased when recurrent carotid artery stenosis is associated with carotid aneurysm. During postoperative surveillance after endarterectomy, the identification of recurrent carotid artery stenosis requires evaluation for aneurysmal degeneration of the carotid artery with duplex scanning. These patients are at significant risk for transient ischemic attack and stroke. This rare complication merits operative repair.

Aneurysm↗
PubMed1992

Use of stress thallium imaging to stratify cardiac risk in patients undergoing vascular surgery.

Reduction of the cardiac morbidity associated with major vascular procedures requires identification of high risk patients prior to operation. This retrospective study reviews the records of 126 consecutive patients who underwent 141 major vascular procedures to determine the accuracy of preoperative clinical, laboratory (ECG), and cardiac function testing (stress thallium-201 scintigraphy, left ventricular ejection fraction scan) in predicting perioperative cardiac complications. An abnormality on oral dipyridamole or treadmill thallium imaging was demonstrated prior to 71 (61%) of 116 procedures and included 20 fixed and 51 reperfusion (reversible) defects. No patient died within 30 days of operation, but 11 minor (ventricular arrhythmia) and 15 major (myocardial infarction, ischemic congestive heart failure) cardiac complications occurred. A reperfusion defect on stress thallium imaging accurately (94% sensitivity, 56% specificity, 98% negative predictive value) identified high-risk patients while accepted clinical rating systems (Goldman, Cooperman, Eagle) and preoperative level of left ventricular ejection fraction were less predictive of adverse cardiac events. Patients without myocardium at risk by coronary angiography, but a reperfusion defect on stress thallium imaging were found to be at high risk for a cardiac complication. The study data support the use of stress thallium imaging to stratify cardiac risk prior to major arterial surgery.

Adult↗
PubMed1992

Wound complications of the in situ saphenous vein bypass technique.

Wound complications after in situ saphenous vein bypass occur frequently, lengthen hospitalization, and threaten graft viability. From May 1981 to March 1991, 117 consecutive male patients underwent 126 in situ operations: 45 (36%) femoropopliteal, 75 (59%) femorotibial, and 6 (5%) grafts to the dorsal pedal artery for gangrene or ulcer (n = 69), rest pain (n = 54), or claudication (n = 3). Wound complications developed in 55 grafts (44%): erythema developed in 11, but they healed primarily, 19 had skin edge necrosis or localized lymph leaks, 12 had necrosis or infection into the subcutaneous tissue without danger to the graft, and invasive infections that threatened the graft developed in 13. Risk factors for a subsequent wound infection included the development of a lymph leak (p less than or equal to 0.05) and early postoperative graft revision for thrombosis, wound hematoma, retained valve or arteriovenous fistula (p less than or equal to 0.05). The mean time to appearance of a graft-threatening wound infection was 31 days, and 10 of 13 were located in the distal limb. Twelve of the 13 deep infections required operative debridement, and seven required a flap or split thickness skin graft for coverage. Gram-negative as well as gram-positive infections responded equally well. No grafts were lost, and no deaths occurred. Despite the high incidence of wound complications, an aggressive therapy regimen permitted universal graft salvage.

Adult↗
PubMed1992

Pitfalls in the use of color-flow duplex ultrasound for screening of suspected arterial injuries in penetrated extremities.

We compared color-flow duplex ultrasonographic scanning (CFD) to arteriography in 67 patients who sustained 75 penetrating injuries to the extremities without obvious arterial injury. There were 72 negative and three (4.0%) positive CFD studies and no failed attempts. With arteriography as the "gold standard," CFD had a specificity of 99% and a sensitivity of 50%, positive and negative predictive values of 66% and 97%, and an accuracy of 96%. Small pseudoaneurysms were missed in an axillary and an aberrant radial artery, and a genicular artery pseudoaneurysm was misread as originating from the popliteal artery. Cautious interpretation of negative studies appears warranted, particularly in the axilla and in bifurcated arteries. Extremity arteries should be completely imaged to rule out aberrant anatomy. Questionable studies should be confirmed arteriographically. With these caveats, color-flow duplex scanning may be useful for screening extremities with penetrating injuries thought to harbor occult arterial injuries.

Angiography↗
PubMed1992

The role of duplex scanning versus angiography in predicting outcome after balloon angioplasty in the femoropopliteal artery.

Duplex-derived velocity measurements were used to assess the hemodynamics of 64 femoropopliteal arterial sites in 59 patients after angiographically successful percutaneous transluminal balloon angioplasty. With use of angiography as the gold standard, percutaneous transluminal balloon angioplasty was judged to be successful if (1) evidence existed of a "split" caused by intimal dissection and splitting of atherosclerotic plaque; and (2) no significant diameter-reducing residual stenosis was observed at the percutaneous transluminal balloon angioplasty site. At 1 month, 55 limbs (86%) were hemodynamically and clinically improved by SVS/ISCVS clinical criteria for chronic limb ischemia. Of the 55 percutaneous transluminal balloon angioplasty sites, duplex scanning had identified 40 (63%) sites with a less than 50% diameter-reducing stenosis and 15 (27%) sites with a greater than 50% diameter-reducing stenosis within a week after percutaneous transluminal balloon angioplasty. Independent review of the 55 angiograms taken after percutaneous transluminal balloon angioplasty identified 39 sites (71%) with a split and 16 sites (29%) without. By life-table analysis, a greater than 50% diameter-reducing stenosis predicted a worse clinical outcome (15% at 1 year) compared with the presence of a less than 50% diameter-reducing stenosis (84% at 1 year) (p less than 0.001; log rank test). The presence or absence of an angiographic split was not a predictive factor of percutaneous transluminal balloon angioplasty outcome (split, 61% at 1 year; no split, 62% at 1 year) (p = 0.832; log rank test). The detection of a functional residual stenosis by duplex scanning did not correlate with angiographic appearance, but was predictive of clinical failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Monitoring functional patency of percutaneous transluminal angioplasty.

Duplex scanning and Doppler-derived blood pressure measurements were used to serially monitor lower limb hemodynamics in 73 patients who underwent percutaneous transluminal angioplasty. Ninety percutaneous transluminal angioplasty sites judged technically satisfactory by arteriography were evaluated. Significant hemodynamic improvement was seen in 81 (90%) of the 90 limbs, although both hemodynamic and clinical improvement were achieved in only 77 (86%) limbs. Duplex scanning within 1 week of successful angioplasty identified moderate (20% to 49% diameter reduction) or severe (greater than 50% diameter reduction) residual stenosis in 49 (63%) of 77 balloon-dilated arterial segments. The presence of a greater than 50% diameter reduction residual stenosis predicted further restenosis and late clinical failure (11% success rate at 1 year). When the degree of residual stenosis at the percutaneous transluminal angioplasty site was less than 50% diameter reduction by duplex scanning, the procedure was durable (80% success rate at 2 years), even in patients with critical ischemia, poor runoff, or diabetes mellitus.

Angioplasty, Balloon↗